Click for next page ( 2

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement

Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 1
Summary of Conclusions and Recommendations In this report we analyze the findings of research published since the early 1800s on the progression and prevalence of myopia (nearsightedness). We show that, although problems arise from the use of the myopia literature, it is possible to draw certain inferences about changes in myopia in certain populations. One concern was whether there have been significant changes over time in the prevalence of myopia among young adults who are eligible for military academy training. Another involves the nature and progression of myopia among young adults. Although we encountered interpretation difficulties with many of the studies and reports we surveyed, we believe our conclusions are reasonable. Highlighted below are some of the most important points we make in our report, cross- referenced to the appropriate sections of the document (a glossary of technical terms appears in Appendix E): Studies of the prevalence of myopia during the past 100 years indicate no signifi- cant change in the distribution of refractive errors within the groups of Caucasian schoolchildren and college-age young adults. An exception to this finding is that high or severe myopia is less prevalent now at all ages (pp. 10-11, 48-50~. . Myopia can start and can increase after age 16, although it is less severe and appears limited to a smaller proportion of these individuals. The degree of myopic change or shift among young adults is apparently small enough to go undetected in cross-sectional studies of the general population (pp. 23-25, 72-73~. . From 1812 to the present, studies indicate that myopia is much more prevalent among college students and young adult males who enter military officer training than among other populations at similar ages (pp. 19-21, 74-78~. Doing near work places one at risk for myopia. On the basis of all studies reviewed, we estimate that as many as 20 to 40 percent of low hyperopes (those who are slightly farsighted) and emmetropes (those without refractive error) who enter colleges and military academies or pursue occupations with extensive near work requirements are likely to become myopic before the age of 25. For populations in which selected college and special near work groups have been excluded, less than 10 percent of emmetropes and low hyperopes will develop myopia prior to becoming presbyopic (pp. 26-33, 59~. Prevalence of myopia has been correlated with level of family income, level of education of parents, refractive status of parents, reading ability, scholastic success, and intelligence (pp. 10-11, 60-61~. o 1

OCR for page 1
2 . Young adult myopes appear more at risk for myopic shift than nonmyopes. Some portion of young adults who became myopic as children progress after a period in which their myopia has become stable; others without myopia develop it as young adults. Although available onset data are difficult to analyze, they generally indicate that myopic shifts among Tow hyperopes and emmetropes are less frequent and less severe than among myopes. Medium and high hyperopes are less at risk for myopic shifts than others (pp. 22-24, 68-70~. Military academies should collect standard refractive information about optical components of the eye (e.g. corneal curvature, lens power, length of eye) under controlled conditions. The necessary technology and human resources are at hand to determine the risk factors related to the causes, progression, optical components, and consequences of adult onset myopia. For example, the length of the eye can be followed to determine if those eyes that ultimately become myopic show early fundus signs (signs of change at the back of the eye) that would identify those eyes at increased risk of undergoing future elongation (pp. 39~. It is important to know what anatomical or functional changes are responsible for young adult myopia. We therefore recommend that research be conducted to determine how each of the optical components of the eye contributes to refractive state and to refractive change (pp. 39~. Study designs should be standardized so that the results of various investigators can be compared. Initial suggestions are offered, more to focus discussion that will lead to consensus than to propose them as final solutions (pp. 39-41~.